Functional vasoactive intestinal polypeptide (VIP)-system in salt glands of the Pekin duck

Summary In saltwater-acclimated ducks with fully specialized supraorbital salt glands, intracarotid application of acetylcholine (5 nmoles/min/kg b.w.) or porcine vasoactive intestinal polypeptide (pVIP) (240 pmoles/min/kg b.w.) induced secretion from the salt glands at threshold conditions of secretory activity. pVIP-like immunoreactivity could be localized in fibers of the postganglionic secretory nerve ramifying throughout the glandular parenchyma. Both middle-sized arterioles and secretory tubules were innervated, and pVIP-immunoreactive varicose fibers formed peritubular baskets around the basal region of secretory tubules indicating direct innervation of the secretory tissue. pVIP-specific staining could be abolished by preabsorption of the antiserum with peptide extracts of salt-gland tissue. Synthetic pVIP and endogenous VIP from salt glands of the duck co-eluted on the HPLC system, suggesting structural similarity of the peptides. Membrane-binding studies with radioiodinated pVIP revealed the presence of high-affinity binding sites in salt-gland tissue. Affinities of unlabeled pVIP analogues to compete for these binding sites were as follows: pVIP > PHI > pVIP antagonist > secretin > pVIP (10–28) > chicken VIP (16–28). Peptide extracts of salt glands had affinities similar to pVIP. Binding sites could be localized mainly at the apical end of the radially arranged secretory tubules, as demonstrated by receptor autoradiography.It is concluded that, in addition to the classical parasympathetic transmitter acetycholine, VIP serves as neuromodulator/transmitter in cranial parasympathetic control of avian salt-gland secretion by acting on both the arteriolar network and the secretory tubules of the gland.     

Lack of physiological stimulation induces decreased proteolytic activity in nerve terminals

The effect of optic nerve transsection on proteolytic degradation of axonally transported proteins in the superior colliculus of the rabbit was studied. Proteolysis of labeled proteins was determined in vitro in small pieces of the superior colliculus. Within 2 hours after sectioning the optic nerve there was a decreased degradation of slowly transported labeled proteins in the nerve terminals in the superior colliculus.Special Issue dedicated to Prof. Holger Hydén.     

Activity patterns and egg production in Coccophagus bartletti, an aphelinid parasitoid of scale insects

ABSTRACT.

• 1 Daily patterns of oviposition and host-feeding were examined in Coccophagus bartletti Annecke & Insley. Females began to host-feed and oviposit during the second or third day after emergence. Thereafter, both activities occurred regularly.
• 2 During long observation periods (5 h) most oviposition (93%) and host-feeding (90%) occurred within the first 3.5 h of wasps first encountering hosts. Experiments demonstrated that levels of activity were low for the rest of the day, and nocturnal oviposition occurred only if wasps had no alternative.
• 3 Dissection of female wasps that had been exposed to hosts, or withheld from them, for given periods of time, revealed that activity levels are governed by egg availability. Dispersal activity may also be influenced by the physiological state of the ovaries.
• 4 Production of a full complement of eggs (at 24±1°C (12 h L) and 18±1°C (12 h D)) took 48h or longer after host-feeding, and if wasps were withheld from hosts and provided with honey, the effects of egg resorption could be detected after about 10 days. Trends in oögenesis and oösorption in C. bartletti females seem not to conform with interpretations of oögenesis-oösorption cycles in other parasitoids.
• 5 The pattern of activity exhibited by C. bartletti females is not inflexible, but the major aspects mentioned above are species-specific. In general, information is needed about daily and hourly patterns of parasitoid oviposition and host-feeding before experiments are designed to test theories of parasitoid behaviour. Interpretation may otherwise rest on assumptions about their physiological condition.

     

The response ofPlantago lanceolata L. andP. major L. spp.major to nitrate depletion

To study aspects of the ecology of grassland species, in a comparative experiment, plants ofP. lanceolata andP. major were grown in pots in a greenhouse, and subjected to a gradual nitrate depletion for several weeks. Control plants were weekly supplied with nitrate. Growth, leaf appearance and disappearance, concentrations of cations and inorganic anions, soluble and insoluble reduced nitrogen concentrations,in vivo nitrate reductase activity (NRA) and the concentration of non-structural carbohydrates in several parts of the plants were followed. Depletion of nitrate caused a reduction of shoot growth, both in biomass and number of leaves. Withering of leaves increased. Accumulation of root dry matter was little (P. lanceolata), or not (P. major) affected. The concentration of reduced nitrogen in all tissues also decreased, both that of the soluble and that of the insoluble fraction. As a result, nitrogen use efficiency (NUE, g dry matter produced per mmol N incorporated) increased by nitrate depletion. NRA was higher in the roots than in the leaves, and decreased with increasing nitrate depletion. In control plants, nitrate became also limiting. This resulted in decreasing nitrate concentrations in leaves and roots. In the leaves, the decrease in nitrate concentration was preceded by a decrease in NRA. The decrease of the nitrate concentration was parallelled by an increase in the concentration of soluble sugar. No major differences in the response towards nitrate depletion were observed between the two species. Grassland Species Research Group, publication no. 129     

Plasmalemma- and tonoplast-ATPase activity in mesophyll protoplasts,vacuoles and microsomes of the Crassulacean-acid-metabolism plant Kalanchoe daigremontiana

Adenosine-triphosphatase activity on the plasmalemma and tonoplast of isolated mesophyll protoplasts, isolated vacuoles and tonoplast-derived microsomes of the Crassulacean-acid-metabolism plant Kalanchoe daigremontiana Hamet et Perr., was localized by a cytochemical procedure using lead citrate. Enzyme activity was detected on the cytoplasmic surfaces of the plasmalemma and tonoplast. The identity of the enzymes was confirmed by various treatments differentiating the enzymes by their sensitivity to inhibitors of plasmalemma and tonoplast H⁺-ATPase. Isolated vacuoles and microsomes prepared from isolated vacuoles clearly exhibited single-sided deposition on membrane surfaces.Abbveviations CAM Crassulacean acid metabolism - H⁺-ATPase proton-translocating ATPase     

Activity budgets and use of enclosed space by wild boars (Sus scrofa) in captivity

This research was conducted on a captive group of eight wild boars: Four wildborn adults (one male and three females) and four piglets (one male and three females), born in captivity two months before the beginning of the study. They were housed in the Rome Zoo in a 1,000 sq m enclosure furnished with trees, mud pools, a water basin, and two small barns. Data on eight behavioral states (sleeping, resting, rooting, eating, walking, standing, scratching, and nursing) were collected by instantaneous sampling at 10-minute intervals. The spatial location of each subject was also noted, as well as closeness to conspecifics. Results showed that adults and piglets differed in their activity budgets. Activity patterns showed a significant correlation with the mean temperatures. Furthermore, there was a significant difference in the use of the exhibit areas between adults and piglets. This study suggests a social structure in which the core is constituted by females and their yearlings. The nonbreeding female has a more marginal position than the breeding ones. Finally, the male tends to be even more peripheral and solitary. Our results are partly consistent with the data obtained in studies on free-ranging wild boars (Mauget, 1980; Dardaillon, 1984).     

Correlation of immunomodulatory and therapeutic activities of interferon and interferon inducers in metastatic disease

The mechanism of therapeutic activity of recombinant murine interferon-gamma (rMu IFN-gamma) and the IFN inducer polyinosinic-polycytidylic acid solubilized with poly-L-lysine in carboxy methyl cellulose (pICLC) in treating metastatic disease was investigated by comparing effector cell augmentation with therapeutic activity in mice bearing experimental lung metastases (B16-BL6 melanoma). Effector cell functions in spleen, peripheral blood, and lung (the organ with tumor) were tested after 1 and 3 weeks of rMu IFN-gamma or pICLC administration (intravenous, three times a week). In these studies, natural killer (NK), lymphokine-activated killer (LAK), cytolytic T lymphocytes (CTL) (against specific and nonspecific targets), and macrophage tumoricidal and tumoristatic activities were measured. rM IFN-gamma and pICLC had therapeutic activity and immunomodulatory activity in most assays of immune function examined. Specific CTL activity of pulmonary parenchymal mononuclear cells (PPMC), but not in splenocytes or peripheral blood lymphocytes (PBL), during week 3 and not during week 1, correlated with the therapeutic activity of rMu IFN-gamma and of pICLC. Macrophage tumoricidal activity in PPMC, but not in alveolar macrophages, also correlated with the therapeutic activity of rMu IFN-gamma, but the opposite was true for the therapeutic activity of pICLC. NK activity of PPMC, but not of splenocytes or PBL, during week 1 correlated with the therapeutic activity of pICLC; in contrast, NK activity at any site did not correlate with the therapeutic activity of rMu IFN-gamma. LAK activity at any site did not correlate with the therapeutic activity of either agent.     

The ecology of a beech forest on Mt. Sanpoiwadake,Hakusan National Park,Japan II. The correlation of the subassociation within the Lindero membranaceae-fagetum crenatae association and environmental parameters

Detailed examination of a sample plot covered by the Lindero membranaceae-Fagetum crenatae association on Mt. Sanpoiwadake, Hakusan National Park, revealed a number of correlations between the distribution of subassociations and environmental factors. The subassociations on the south-facing slopes receive deep snow cover in winter with rapid melting in the spring. They occur on porous, freely draining soils, typical of the general range of brown forest soils. Conversely, on the north-eastern slopes there are widespread late-snow patches which delay leaf development and expansion and which provide an abundant water supply well into early summer. Under these conditions, bleached soil horizons have developed with iron pan formation, resulting in poor soil drainage, strongly correlated with quite different plant communities.     

Microbeam analysis of Ca exchange and uptake in the fine roots of spruce: influence of pH and aluminum

Summary A novel stable isotope labelling procedure for microbeam analysis was developed to monitor exchange and uptake of nutrients, primarily Mg, K and Ca, by root tips at the cellular level. Initially root samples were analysed from 2-year-old spruce trees, originating both from a nursery and from a polluted forest site, (1) for the cortex cell wall accessibility and nutrient binding properties, (2) for the influence of low pH and elevated aluminum concentrations on Ca binding to cortex cell walls, and (3) for long-range transport into the secondary xylem, proximal to the labelled root tip. In nursery control plants, Ca is localized mainly in the apoplast of the cortex. Exchange of Mg, K, Ca in the cell wall of the cortex and the primary xylem with label in incubation solutions is almost completed to equilibration within 30 min. In the secondary xylem we could detect Mg, K, and Ca from labelling solutions in minute amounts after 30 min, and as a major fraction after 48 h. This indicates that stable isotope labelling can be used to study both ion-exchange properties of the apoplast and long-range transport. Slight acidification of the labelling incubation media to pH 4.5 reduced Ca binding to the cortex cell walls slightly, but acidification to the extreme value of pH 2.3 reduced binding 41%. A combination of pH 4.5 and increased free aluminum reduced the binding by 83%. In a preliminary attempt to analyse the nutrient binding capability of the root-tip apoplast from pollution affected trees, we exposed fine roots of 2-year-old spruce from an acidified and polluted site showing typical low levels of Ca and Mg in the cortical cell walls to Ca-enriched media. Under these conditions the Ca content of cortex cell walls doubled upon incubation at pH 4.7, reaching 40% of the total binding capacity of our nursey control plants.